Volatile halogenated organic compounds can be removed from the water by physical methods such as air stripping or filtration through sorptive media such as charcoal. These methods are phase-transfer processes and the off gases or the charcoal must be subsequently treated. Because of the low aqueous solubility of many compounds removal from the subsurface by pumping water has proven to be ineffective.
In addition, some anaerobic bacteria have been demonstrated to biodegrade many of the above-mentioned compounds by co-metabolism. This means that the bacteria do not derive any energy from the process, therefore, they must be fed an alternate carbon source. The rate of reaction is usually slow with a half-life of days to weeks and as a second drawback, the bacteria are susceptible to toxic concentrations of the chemicals.
Recently, certain biochemicals have been shown to mimic the bacterial process in vitro. Examples of such compounds are hematin and vitamin B12. Vitamin B12 belongs to the class of compounds called the corrinoids, a multiple pyrrole ring system with a chelated metal (ie. Fe, Ni, Co) in the centre. Corrinoids have been very effective in reductive dechlorination of chlorinated organic compounds in the absence of a cell or protein structure, which is often thought to be essential for correct alignment of the substrate with the catalytic centre of the enzyme. Corrinoids in general, and vitamin B12 as an example, are capable of reductively dechlorinating chlorofluorohydrocarbons, chlorinated aliphatic hydrocarbons and aromatic hydrocarbons. However vitamin B12 has not been used in the in-situ treatment of contaminated soil or ground water.
U.S. Pat. No. 5,044,551, issued Apr. 2, 1991 provides a method for treating water or solids contaminated with at least one chlorinated phenol and involves the oxidation of the phenol in the presence of a catalytic mount of a corrin or porphyrin metal complex. One example of the porphyrin metal complex is given as an iron ion (Fe.sup.3 +). The method set forth in this patent is limited to an oxidation process. An oxidation process requires the presence of an easily oxidized functional group imparted by the presence of an oxygen atom, as in phenols, a sulphur atom or a nitrogen atom. It is the oxygen that is bound to the catalyst and accordingly, the process of the '551 patent would not be applicable to halogenated hydrocarbons which do not contain hetero atoms (O, N, or S) which make them susceptible to oxidation.
Other prior art references which are generally related to catalytic degradation of compounds includes U.S. Pat. Nos. 3,252,892, issued May 24, 1966, to Gleim and U.S. Pat. No. 5,051,030, issued Sep. 24, 1991, to Saha et at.
In view of what has been previously proposed in the prior art, it is clear that a need exists for a process which can proceed to dehalogenate contaminated ground water or effluent and/or soil contaminated with halogenated organic compounds and which does not further add environmentally hazardous compounds in the process of dehalogenating the halogenated compounds. The present invention is directed to satisfying this need.